Reheater



1931- 'w. H. ARMACODST 1,818,446

REHEATER Filed Jan; 28, 193D INVENTOR. Wilbur H.Armncos1;'

( f/7cm A TTORNEY.

Patented Aug. 11, 1931 UNITED STATES PANY, or new YORK, N. Y.

PATENT OFFICE WILBUR H. ARMACOST, OF NEW YORK, N. Y., ASSIGNQB TO SUPEBHEATER coM- v REHEATER Ap plication. filedoJ'anuary 28, 1930. Serial in). 423,966.'

known piece of apparatus and in its usual form includes a shell having an internal partition forming two passes, one of which contains tubes for heating fluid. This type of apparatus although preferred for certain conditions has bee-n foundto suffer from heat transfer through the internal partition from the hot fluid to the cold.

It is an object of my invention to provide means in a two-pass heat exchangerwhich shall substantially eliminate the difficulty just mentioned. I j

A further object of my invention is to provide compact arrangements of the heating tubes of heat exchangers.

Still another object of my invention is to provide tube units for heat exchangers adapted for ready insertion and removal from the apparatus when desired.

The novel features of my invention are pointed out in the appended claims. The invention itself, however, together with further objects and advantages, will best be understood from a detailed description of a specific heat exchanger embodying the invention,

and such a description will now be given in connection with the accompanying drawings in which Fig. 1 1 is a central longitudinal section through a two-pass 'exchangerin accordance with my invention. r

Fig. 2 is a fragmentary sectional view of the upper portion of the apparatus shown in Fig. 1 and taken on a vertical plane including line 22 of Fig. 3.

Fig. 3 is a sectional plan of the apparatus illustrated in Fig. 1, the left-half of Fig. 3 being taken on a plane in the upper part of the apparatus and the right hand half of Fig. 3 being taken on a plane through the inlet and outlet.

Fig. 1 is a fragmentary horizontal section illustrating one manner of bracing the tube units of Fig. 1 against lateral movement.

lustrating the manner of attaching the tubes of a unit to a vertical hanger.

Fig. 6 isafragmentary vertical section on the same plane as Fig. 2 of a portion of the apparatus of Fig. 1 and-illustrating the bot- .tomsupport for the tube unitsand the lower end of a'dead space. r e

The illustrative embodiment of the invention shownin the drawings is a steam reheater of the well known two-pass type and shown as having its axis vertical with the inlet and the outlet for the steam to be heated placed at its lower end. 'The shell of the heat exchanger is indicated at 14' and the inlet and outlet are at16 and 18 respectively. The inlet is separated from the outlet by an interior partition 20 running upwardly from the bottom of the shell 1a and forming an upward pass 22 and a downward pass 24 connected at their upper ends. A bundle T of coiled heating tube-s is shown substantially filling the pass 22, and headers 26 and 28 are provided for supplying heating fluid such as superheated steam to and receiving such fluid from the coils in bundle T. As shown, the headers 26 and 28 are inserted into the lower portion of the pass-22 through the shell 14, the outer ends of the-headers projecting through the shell and having flanges 3O threaded thereon for positioning. the headers and contacting with the faced fittings 32 for this purpose, the fittings 32 being fixed to the shell 14.

.The inlet and'out-let ends of the serpentine sections 36 are detachably secured to the headers 26. and 28 by a suitable means 66.

It will be seen that the ingoing and outgoing streams of fluidon opposite sides of the partitionu20,have different temperatures at any given level so that there has been a trans fer of heat from the outgoing to the ingoing stream through the partition of .a two-pass heat exchanger, reducing the volumetric and .the commercial efficiency of the apparatus.

It is a featureof the present invention to minimize such a transfer of heat to the ingoing fluid by running the inlet sections 34 and 34a of the tubes in the bundleT from the inlet header 26 along the partition to heat it. As illustrated, the inlet sections 3% and 34-11 Fig. 5 is a fragmentary vertical section il- 'temperatures.

of the tubes in bundle T spread across the entire width of partition 20 and run upwardly adjacent the partition for almost its entire length thereby maintaining the partition at a temperature at least as high as that of the outgoing fluid and effectively preventing transfer of heat from the outgoing'to'the ingoing fluid.

It is a feature of the invention to build up a tube bundle T of units of substantially the same size and so arranged as to be conveniently assembled and removed fromthe apparatus. For this purpose, the partition 20 is curved in a horizontal planeon a radius substantially the same as that of shell .14. Thehorizontal distance between the convex side of the partition 20 and shell 14 is thereby made uniform on all lines parallel to'the central radius of the partition and I have used such a space for the pass22 thereby'beenabled to build up the bundle T of units of uniform dimensions; As illustrated, the upper ends of the. inletsections 34 and 34a of the tubes connect to serpentine tube sec- 1 itio'ns 36 which are bent back and forth in vertical planes on bends of substantially .180" curvature thereby forming a series of serially connected U loops, each serpentine section lying, as shown in Fig. 1, substantially in a vertical plane throughout. As appears fully from Figs. 1 and 3, the serpentine sections 36 are of substantially uniform Tsize and extend the full horizontal distance between the partition 20 and shell 14 in pass 22. The sections 36 lie close togetherand fill the entire space of the pass with only suflicient clearance between the tubes for passage ofsteam. or other fluid to be heated. 'lhe'segments 38 within the shell 14 lying at the ends of the partition 20 evidently will not accommodate serpentines of the same horizontal dimension as sections 36, and, in order to avoid special-tube units for such segments, the pass .22 is spaced from the shell 14 along the vertical edges of the partition 20 by flat vertical plates such as40 (Fig. 3). In order to prevent fluid to be heated from freely bypassing the tube bundle T through segments 38, each of such segments "is closed at its bottom by a plate 42 (Fig.6).

It is preferred also to close the tops of segments 38 by plates 42a (Fig. 2) so that any steam leaking into segments38 cannot escape from them without passing through the heating pass 22. It has been found desirable jmoreover to divide plate 40 by a slip joint 41 to permit relative movement of the two parts of said plate. As shown, joint 41 runs parallel to the longitudinal axis of the exchanger intermediate the joints betweenplate 40 and shell 14. Such a joint prevents undue stresses in the plate and its connections when different parts of the reheater are at different A feature of my invention whereby the "unit for insertion into and removal from the r-eheater. At their lower ends, the tube units may restuponcross'beams 52 and the curved sections of the serpentines 36 are shown in Fig. 4 as braced against lateral movement or vibration by channels 54, welded to themner face of shell 14. It willbe seen that by 'removing the cover 56 of the shell and by disconnecting the tubes of'a given unit from the headers. 26 and 28, any unit can be easily taken out of the shell and afterwardreplaced in a reverse manner.

Another feature of the invention resides in the particular form'of the elements of the tube bundle. For reasons not involved inthe present invention, bifurcated tubes have'been proposed for use in heat exchangers. I, therefore, have illustrated the serpentines of the tube bundles as formed of bifurcated tubes. In the arrangement illustrated in Figs. 1 to 6, the inlet sections 34, 34a of the tube units are of the single tube type, the inlet sections 34,34a being bifurcated at 57 to form serpentines 36 the halves of which are reunited at 61 to form outlet sections 62 and 62a of the single tube type. However, to obtain the maximum heating surface in a given space with such an arrangement, I find it necessary that the inner bends 58 of th.e'bifurcated tubes of the serpentines be formed by welding together the adjacent lengths or runs of tubing,

a maximum number of tubes in a given pass or space that it is diflicult to provide room on headers of moderate size formaking the connections between the heating tubes and the headers. In order further to provide space for attaching the tubes to the headers, tube sections 34 are attached to a header 26 in a row 64 which is spaced angu'larly from the row 65 along which the tube sections 34a are secured to 'the header. A similar arrangemerit -is employed also for connecting -'tube sections 62 and 62a to header '28. -Manhole structures '68 are provided in the bottoms of the exchangers and in thecovers 56- thereof for permitting enteringshells when desired.

In operation, steam to be reheatedenters shell 14 at 16, passes u'p'aroundandin contact with the heating coils of bundle T in pass 22, down the pass 24 and out'through the outlet 18, the parasitic transfer of heat from steam in pass 24 to that in pass 22 is prevented almost entirely by keeping the temperature of partition 20 substantially equal to that of the steam in pass 24 by heat from the tubes 34 and 34a arranged close to partition 20.

I claim:

1. A heat exchange apparatus comprising a shell, a partition in said shell defining a portion of the wall surface of a pass through the shell, a plurality of elements for conveying a heating fluid located in said pass, the inlet portions of said elements being disposed adjacent to said partition.

2. A heat exchange apparatus comprising a shell, a partition dividing said shell into two longitudinal passes, a plurality of elements for conveying a heating fluid located in one pass, the inlet portions of said elements lying adjacent to said partition along the major portion of its length.

3. A heat exchange apparatus comprising a cylinder shell, a partition dividing said shell into two longitudinal passes, said partition being transversely curved on substantially the same radius as the radius of the shell, whereby one pass of uniform width is formed between the partition and the wall of the shell, and a plurality of tubular heating elements located in said pass, each of said elements comprising a series of serially connected U-loops disposed transversely of said pass across its uniform width.

4. In a heat exchanger, the combination of a chamber, headers in said chamber, elements in said chamber having sections running adjacent the wall of said chamber and reversely curved sections substantially filling the crosssection of the chamber, detachable joints for connecting said elements to said headers, and means for supporting said elements in said chamber so arranged that the elements and supports may be removed from the chamber in individual units.

5. In a heat exchange apparatus, the combination of a chamber, headers in the lower part of said chamber, elements suspended from the upper portion of said chamber and having inlet sections running adjacent the wall thereof and reversely curved sections substantially filling the cross-section of the chamber, detachable joints for connecting said elements to said headers, and means for supporting said elements in said chamber so arranged that the elements and supports may be removed from the chamber in individual units.

6. A coil element for heat exchanger having single tube portions for connection to headers and a bifurcated intermediate serpentine portion, said serpentine portion comprising two parallel tubes winding back and forth and having reverse curves at which the tubes lie in the same plane, the inner one of a given pair of coplanar curves comprising welded ends of adjacent tube runs. 

